Electric resistance furnace



ELECTRIC RESISTANCE FURNACE Filed April '7, 1922 2 sheets-shah 1 WITNESSES: INVENTOR 7 1%? (9 GeweML/W/e.

'Jan. 1, 1924 G. M. LITTLE ELECTRIC RESISTANCE FURNACE 2 Sheets-Sheet 2 mm g INVENTOR Gauge .L/fi/e.

TTO'RNEY WITNESSES: j C l6.- 1/ 7w 5% Patented 'J l, 1924.

UNlTEDfSTATES PATENT OFFICE.

' GEORGE M. LITTLE, PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSE ELECTRIC Q MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

'nnac'rmc ansrsrmcii runner,

Application filed April 7, 1922. Serial No. 550,388.

To all whom it may concern:

Be it known that I, GEORGE M. LIrrLE, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electric Resistance Furnaces, of which the following is a specification. t

My invention relates to electric furnaces l0 and particularly to electric-resistance furnaces, and it has for one of its objects to provide a relatively simple furnace structure that shall permit of simultaneously heat-treating a variety of materials.

Another object of my invention is to provide a plurality of elongated tubular mufiles located in a furnace chamber and heatedv only at substantially the middle portions thereof to provide first an increasing and then a decreasing temperature for "material moved therethrough.

In practising my invention, I provide a plurality of refractory walls enclosing a furnace chamber and locate therein a rela- 2 tively narrow, elongated, built-up refractory resistor member resiliently supported between two opposing walls. A plurality of elongated, refractory, tubular members are located in spaced-apart relation in the furnace chamber above said heating element and extend transversely thereof. A twopart water-cooled member is clamped on.

the adjacent ends of the tubular members to maintain them in proper operative positions relatively to each other and to permit of cooling the ends of the tubular mufiles.

A motor-operated means is provided for causing material tobe heat-treated in said tubular members to be moved therethrough.

In the drawings,

Figure 1 is a view, in vertical longitudinal section, of an electric-resistance furnace embodying my invention;

Fig. 2 is a view, in vertical lateral crosssection, of such an electric furnace;

Fig. 3 isa top plan view of an electric furnace embodying my" invention, with means for moving material therethrough;

Fig. 4 is a view, in side elevation, of a material-moving'means;

F 'g. 5 is a schematic outline of a gear train comprising a part of the materialmovin means.

is provided and comprises a suitable re Ane ectric furnace,designated generally by the numeral 11, comprises anouter metallic framework or casing 12 within which is located an outer layer 13 of suitable heat-insulating'bricks or blocks which may be sil-ocel or any other suitable refractory material. An inner lining 14 comprises a plurality of bricks or. blocks of a suitable hightemperature-resisting refractory material, such as firebrick. The bricks or blocks constituting the two linings 13 and 14. are so shapedand disposed as to provide a furnacechamber 15 of any suitable or desired dimensions. An opening .16 is rovided adjacent the bottom at one end 0 the furnace structure, normally closed by a door 17, to 7 end of an elongated refractory electrode 21 I which extends through an opening 22 in the end wall of the furnace. A. water-cooled metallic electric-circuit terminal member 23 is provided with a tapering opening 24 which operativly engages the outer conical end of t e electrode 21. The terminal members.23 are provided with lugs 25 to permit of connecting thereto the ends of suitable supply-circuit conductors (not shown). In order to insulate the terminal members 23 from the furnace structure, annular members 26 of a suitable insulating material, such as asbestos, are located in the outer face of the furnace structure in the openings 22. This construction of terminal is described and claimed in my co nding application Serial No. 463,221, file April 21, 1921, and assigned to the Westinghouse Electric & Manufacturing Company. As the length of the heating element 18 is relatively great an intermediate sup ort ctory electrical non-conducting block 27 extending-transversely of the heating element ever, be placed a short distance below the heating element so as not to normally engage the same but to be operative to prevent the collapse of the heating element during the operation of the furnace. In order to prevent the outer ends of the heating element 18 from falling, blocks 28 of a suitable high-temperature-resisting refractory material, such as corundite, may be located in the end Walls of the furnace to constitute the floor of opening 22 and may extend a short distance into the chamber underneath the outer ends of the heating element.- While I have shown these supporting members, these are not an essentialpart of my invention and may be omitted.

A plurality of laterally extending tubular muftles 29 are located in the upper part of the chamber in parallel spaced-apart relation and are each provided with a central axial opening. 31 therethrough to constitute passageways for refractory resistance rods which are moved therethrough by means to be hereinafter described to heat treat the same. I In order to provide a combinedv means for cooling the outer ends of the refractory tubular mufl les 29' and for holding the mullles in proper operative positions relatively to each other, I provide atWo-part till clamping means comprising an elongated upper member 32- and a substantially similar lower member 33'which are clamped to gether at their outer ends by any suitable means (not shown) and which are further v provided with cored chambers to permit of their being traversed by a suitable cooling fluid, inlet pipes 34 and outlet pipes 35 being provided at the ends of each of the members i 32 and 33 to permit of connecting to a suitable source of supply a cooling fluid (not shown).

In order to reduce the amount of heat lost by radiation from the top of the furnace, a plurality of elongated carbon bricks or slabs 36 are located immediately above the tubular members 29 to constitute the roof of the furnace chamber 15. If necessary, I may provide a plurality of carborundum bricks 37 as a part of the inner lining 14 immediately adjacent to. the-heating element 18 and to the tubular members 29 to'insure a relatively long life of the furnace structure. The slabs 36 may be supported by the side walls 37 or in any other approved manner, with the extent of interengaging surface between the slabs 36 and the walls 37 made as sinall as possible to reduce the amount of heat conducted from the walls to the roof. A layer 38 of finely divided heat-insulating material, such as petroleum coke dust, is placed upon the slabs 36 and the upper end of the linings 13 and 14 in order to reduce the amount of heat conducted in an upwardly direction through the linings 13 and 14. I may provide a plurality of bricks or .tallic casing 12 or a reinforciiig blocks of any suitable heat-insulating refractory material to constitute the roof 39 of the furnace structure 11.

In order to provide a means for easily and quickly removing a damaged heating element from the furnace chamber and replacing it by a new one, a portion of one of the side Walls is made removable, as indicated particularly in Fig. 2 at the left-hand side of the furnace structure there illustrated; An angle-iron member 41 may be Suitably'securcd against the top of that part of the metallic casing 12 below the opening in the side wall and a substantially similar angle member 42 may be secured against the lower edge of a portion 43 of the casing to 'permit of bolting the part 43 in its proper operative position and to permit of removing the same and then removing a portion of the lining 13 and 14 and of the lining 37 to permit of removing the heating element l8 laterally from the furnace chamber 15 and of inserting a. new heating element therein.

Each of the tubular members 29 is provided, at each end, with a metallic tubular extension 44, the outer ends of each of which have the top portions thereof cut away and the inner ends of which are enlarged to permit of their being located on the outer ends of the tubular members 29 and of being clamped in place by the clamping members 32 and 33.

vidual plates of the built-up heating element 18 and for pressing the terminal members 23 on the outer ends of the electrodes 21 and for pressing the electrodes 21 against the heating element 18 may comprise any suitable resilient means, here shown as a plurality of studs 45 having threaded ends. The inner ends of the studs 45 suitably engage either an integral portion of the meplate 46 suitably secured to the casing. cross bar 47 is supported adjacent the outer ends of the studs 45 by means of nuts 48 located on the threaded outer end portions of the studs. A helical spring 49 is located between an adjusting member 51 carried by the cross bar 47 and an innerpressure plate 52 which is separated from the outer end of the terminal member 23 by a plate 53 of a suitable elec trical insulating material. While I have illustrated a particular resilient compressing means, I do not desire to be limited thereto, as any suitable or desired construction may be employed.

Means for simultaneously pushing refrac tory resistance rods through the tubular mutlles 29 comprises a platform 54 built up in" any suitable or desired manner, as illustrated in Figs. 3 and 4 of the drawings. An electric motor 55 may be mounted on a portionrof'the platform 54 and be operatively Ill! and extends outwardly thereof. Intermediate the ends of the shaft 63 is located a pinion 64 which is so mounted thereon as to rotate therewith but to have longitudinal movement relativel thereto. A shifting handle 65 controls t e position of the pinion 64 longitudinally of the shaft 63, the handle 65 being pivotally mounted on a bearing member 66 constituting a portion of the pushing mechanism. A stop block 67 is located at the outer end of the shaft 63 to limit the longitudinal movement of, the pinion 64 thereon. The worm gear 62 has an integral extension 68 wvhich is provided with a lurality of jaws to co-operate with a jaw-dlutch member 69 operatively connected to the pinion 64 to rotate therewith.

The pinion 64 operatively engages a gear Wheel71 which is mounted on a shaft 7 2, the gear wheel 71 and the shaft 72 having screwthreaded engagement with each other. The inner end of the shaft 72 operatively engages a plate or block 73, the connection being such that the shaft 72 is permitted to rotate relatively to the block 73. A plurality of rods74 are located on the inner surface of the block 73 and extend therefrom, a perforated guide plate 75 being located at the inner end of the platform 54 to prevent a rotative movement of the block 73 when the shaft 72 is caused to rotate by the hereinbefore described train of gears. The rods 74 rest in the tubular members 44 and serve to push refractory resistance rods to be heat treated in the mufiles 29 therethrough when the train of gears hereinbefore described is so operated as to 'move the shaft 72 longitudinally of its bearing mem-' bers 66 and 76. In order to maintain the platform 54 in proper position relatively to the furnace structure, I connect the same by a plurality of bolts 77 which are secured, at their ends, to angle members 78 and 79, whichare, inv turn, suitably secured against the furnace structure and the platform. When the shaft 72 has been moved to substantially the limit of its travel in the direction of the furnace, it may be brought back to substantially its starting position by means of a pinion 81 which meshes with the pinion 71 and is mounted on a shaft 82 located in suitable bearin members 83 and 84 on the platform 54. 5 hand wheel 85 is mounted on the outer end of the shaft 82 to permit of and, therefore, the pinion 71. When it is quickly rotating the pinion 81' desired to cause refractory, resistance rods to be moved through the tubular members 29, the motor 55 is so operated as to cause the train of gears hereinbefore described to move the shaft 72 toward the furnace, the handle 65 being in substantially the position indicated in Fig. 4. When it is desired to move the shaft 72 and the members oper.-

atively connected thereto back to their origithe furnace are pushed outwardly towards the ends of the left-hand tubular members 54, they ma be removed by the operator.

In or er to provide means for heat-treating metal rods or bars in the furnace cham ber 15 below the heating element 18, I provide a platform 86 located immediately in front and below the opening 16 of tgie furnace and build the'same in any desire or approved manner to permit of locating there on the outer end of articles extending into the furnace chamber. If desired, thedoor 17 may move downwardly to give access to the furnace chamber, and a plurality of pulleys 87 may be provided at the front of the furnace structure to permit of suitably counterweightin the door 17 so that it may easily be opene and closed. As such constructions are well known in the art, it is believed that no-further description thereof is The furnace embodying my invention thus provides means for heating the ends of rods or bars in the furnace chamber while, at the same time, refractory resistance rods are being heat treated in the mufiles located immediately above the heating element and it is only necessary to provide sufficient heat to permit of both of these 0 erations bein'g conducted simultaneously. y making the heating element relatively narrow, it is possible to have a relatively narrow zoneof relatively *high temperature in the mufiles and the temaft ing any serious oxidation of the surface of the resistance rods when being subjected to i such a temperature as would cause oxidation rods moved through said passageways.

thereof if not so protected.

While I have illustrated and described a specific embodiment of my invention, I do not desire to be limited thereto, but to inelude all devices covered by the appended claims.

I claim as my invention:

1. In an electric-resistance furnace, in combination, a plurality of refractory walls enclosing; a furnace chamber, a plurality of refractory muffle tubes extending through said chamber, and a relatively narrow, elongated refractory resistor member located in the chamber below said muflie tubes and extending transversely thereof, thereby 0btaining a predetermined temperature gradient from the intermediate portion of said muffle tubes to the ends thereof.

2. In a combined forging and heat treating electric-resistance furnace, the combination with a plurality of refractory heat-in sulating walls enclosing a furnace chamber, and an opening in one of said walls adjacent the bottom of said chamber to permit of access thereto, -of a relatively narrow, elongated refractoryresistor element extending between certain of said walls in the intermediate part of said chamber and a plurality of spaced-apart refractory muffle tubes located above said resistor member transversely thereof and extending through other of said walls.

3. In an electric-resistance furnace for heat-treating refractory material, in combination, a plurality of refractory walls -enclosing a furnace chamber, an elongated refractory resistor member located in an intermediate portion of said chamber, an opening in one of said walls below said resistor to.

permit of introducing material to be heat treated into said chamber and a plurality of enclosed passageways located in the upper part of sald chamber to permit of simultaneously heat treating a plurality of refractory nae area plurality of refractory walls enclosing a furnace chamber, an elongated relatively narrow refractory heating element located in the intermediate portion of said chamber,

aplurality of elongated refractory tubular members located in the upper portion of said chamber to constitute passageways for said elongated material moved therethrough to heat treat the same and means on .each of said walls for maintaining the end portions of said members at a. relatively low temperature and for maintaining a predetermined temperature gradient between the middle portion of the tubular members and the ends thereof.

6. In an electric-resistance furnace, in

combination, a plurality of refractory walls enclosing a furnace chamber, a plurality of refractory mufile tubes located in the upper part of said chamber and supported by certain of said walls, a relatively narrow elongated heating element located in said chamber-below sald tubes and transversely thereof and means for maintaining the ends of said mufile tubes in proper operative position relatively to each other, said means having integral provision for permitting the cooling of the ends of said tubes.

In testimony whereof, I have hereunto subscribed my name this 21st day of March, 1922.

GEORGE M. LITTLE. 

